title: Oxygen and carbon dioxide tensions, breathing and heart rate in normal infants during the first six months of life.
abstract: Daytime measurements were made of the relationship between sleep state, cardio-respiratory changes and oxygen (transcutaneous PO2) and carbon dioxide (mass spectrometer alveolar PCO2) tensions in eleven normal infants from birth to 6 months of age. Sequential records were made at 1 week, 1, 3 and 6 months. The babies were not restrained, slept in a cot, and were constantly observed. Heart rate was higher in active sleep than in quiet sleep at all ages and rose between 1 week and 1 month (P less than 0.01) in both quiet sleep and active sleep and then decreased at 3 and 6 months. Respiratory rate only changes with age in active sleep at 6 months, showing a decrease (P less than 0.05) but was higher in active sleep that in quiet sleep at 1 month (P less than 0.002) and 3 months (P less than 0.02). A fall in heart rate (less than 100 beats/min) occurred chiefly in association with apnoea. The incidence of apnoea (of greater than 3 s duration) varied widely between babies at the same age and in the same baby at different ages but was most common in the first 3 months of life. No evidence of obstructive apnoea was found and no apnoea of greater than 12 s duration was observed. Period breathing occurred in all babies at 1 month normally following sighs but was uncommon at 1 week and 3 months and absent at 6 months. A fall in transcutaneous PO2 did not precede but often resulted from an episode of periodic breathing.
mesh_terms: D000375:Aging; D001049:Apnea / Q000503:physiopathology; D002245:Carbon Dioxide; D004562:Electrocardiography; D004569:Electroencephalography; D005260:Female; D006339:Heart Rate; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D010101:Oxygen Consumption; D011650:Pulmonary Alveoli / Q000378:metabolism; D012119:Respiration
chemical_list: D002245:Carbon Dioxide